A water treatment apparatus, for example, utilizing activated carbon as shown in FIG. 2 has been known as an apparatus to purify river water to obtain purified water of high quality. In a technique disclosed here, water to be treated is fed from a raw water tank 11 reservoiring a raw water (a) through passages 12, 13 by a raw water pump P1, a circulation pump P2 to a membrane module 14 where suspended solids (SS) are removed, thereby a purified water (b) is obtained. In case of the apparatus shown as example, the apparatus is configured to return water to be treated through a passage 15 for circulation.
Furthermore, in the instance shown in this figure, organic substances such as abnormal taste and odor causing materials, coloring materials and the trihalomethane precursors in the raw water (a) is removed by adding, from powder activated carbon injection means 16, activated carbon of ultra-fine particle powder having a particle size of 0.01 μm to 10 μm, instead of activated carbon powder having a particle size of about 18 μm which has heretofore been used.
However, in such a known method, there has been used activated carbon of ultra-fine particle powder having been milled in advance by a certain method to have a particle size of 0.01 μm to 10 μm, however, such activated carbon of ultra-fine particle powder in itself is apt to aggregate and easily forms a secondary aggregate; thus, there is a problem that effects of careful selection of ultra-fine particle powder are not sufficiently attained. Moreover, there is also such a disadvantage that fine particle powder causes dust in handling.
The present invention has been made to solve the problems described above, and is intended to provide a method of adding activated carbon in a water purification treatment and method of water purification treatment, wherein secondary aggregation of the activated carbon ultra-fine particles can be suppressed to make full use of its adsorption performance and the dusting of activated carbon fine particles during handling can be prevented, in the water purification treatment by which the quality of purified water is improved by utilizing the adsorption of the activated carbon.